A Bf3 Fast Neutron Dosimeter (Long Counter)

A BF3 fast neutron dosimeter or long counter is constructed and calibrated for use with the Cockcroft-Walton accelerator and UTR-IO reactor at Virginia Polytechnic Institute. The counter consists of a paraffin cylinder 8 inches in diameter, having a BF3 proportional detector on the axis and a set of holes around the detector to improve the low energy response. External shields of paraffin, 3 inches thick, and boron-trioxide, 1/2 inch thick, enclose the paraffin cylinder. These shields serve to reduce the background effect and improve the high energy response. Calibration of the counter is accomplished using as neutron sources: plutonium-berylliwn and the induced reactions H2(d,n)He3 and H3(d,n)He4. Long counter efficiencies for both a 1 inch and 1/2 inch BF) tube yield a flat response over the energy range, 2.5 to 4 Mev whereas an approximately 60% decrease in efficiency is observed for a 14.1 Mev neutron. Count rate of long counter is expressed as a function of the incident neutron flux. Neutron fluxes, ranging from 0 to 1100 neutrons/cm2-second are monitored with the counter.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Physics

Department dc:contributor.department

Physics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1960

Author dc:creator

• Leyland, Walter A.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-04262010-020346

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/42283